Fault tolerant system with equivalence processing driving fault detection and backup activation

ABSTRACT

A system includes a primary functionality and a backup functionality for the primary functionality. A measurement circuit measures operational parameter values of the primary functionality. A fault detection circuit determines a level of equivalence between the operation of the primary functionality and a reference functionality based on a weighted comparison of the measured operational parameter values of the primary functionality to corresponding reference operational parameter values for the reference functionality If the equivalence determination fails to find equivalence, the fault detection circuit signals a fault in the primary functionality and activates the backup functionality.

TECHNICAL FIELD

The present invention relates to systems implementing fault toleranceand, in particular, to a method and apparatus for monitoring systemoperation and activating alternate functionality in response to adetected fault.

BACKGROUND

It is common in complex systems, such as electric circuits, for certaincritical functionalities to be supported by a backup or alternatefunctionality. In response to a detected fault in, failure of, ormal-performance by a primary functionality of the system, the providedbackup or alternate functionality is activated. In this way, continuedoperation of the complex system is supported in spite of the primaryfunctionality's fault, failure or mal-performance.

SUMMARY

The present invention is directed to a means for making the fault,failure or mal-performance detection. The operation of a primaryfunctionality of a complex system is characterized by a set ofparameters and, considering an ideal or nominal (or reference)representation of the primary functionality, an expected value for eachof those parameters. The expected value is derived from an applicabledistribution of possible (acceptable) values indicative of properoperation. Measured values of the parameters for the primaryfunctionality are then obtained, and a mean equivalence level iscalculated between the measured operation of the primary functionalityand the ideal representation of the primary functionality. If the meanequivalence indicates that the primary functionality is not operatingconsistent with the ideal representation, a fault, failure ormal-performance detection is made. The complex system may then respondto that detection by replacing the primary functionality of the complexsystem with the backup or alternate functionality.

In an embodiment, a system comprises: a primary functionality; a backupfunctionality for said primary functionality; a measurement circuitconfigured to measure a plurality of operational parameter values of theprimary functionality; and a fault detection circuit configured todetermine a level of equivalence between the operation of the primaryfunctionality and a reference functionality based on a weightedcomparison of said measured plurality of operational parameter values ofthe primary functionality to a corresponding plurality of referenceoperational parameter values for the reference functionality, said faultdetection circuit further configured to identify a fault in said primaryfunctionality based on the equivalence determination and activate thebackup functionality in response thereto.

In an embodiment, an apparatus comprises: a system under test; ameasurement circuit configured to measure a plurality of values foroperational parameters of a system under test, said operationalparameters corresponding to a plurality of values for operationalparameters of a reference system; and a control circuit configured tocalculate an equivalence metric as a sum of relative percentages of theoperational parameter values for the system under test versus theoperational parameter values for the reference system and furthercontrol operation of the system under test in response to the calculatedequivalence metric.

In an embodiment, a method comprises: measuring a plurality ofoperational parameter values of a primary functionality; determining alevel of equivalence between the operation of the primary functionalityand a reference functionality based on a weighted comparison of saidmeasured plurality of operational parameter values of the primaryfunctionality to a corresponding plurality of reference operationalparameter values for the reference functionality; detecting a fault insaid primary functionality based on the equivalence determination; andactivating a backup functionality in response to the detected fault.

In an embodiment, a method for determining an equivalence level to areference system defined by a plurality of values for operationalparameters comprises: measuring a plurality of values for correspondingoperational parameters of a system under test; calculating anequivalence metric as a sum of relative percentages of the operationalparameter values for the system under test versus the operationalparameter values for the reference system; and controlling operation ofthe system under test in response to the calculated equivalence metric.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the embodiments, reference will now bemade by way of example only to the accompanying figures in which:

FIG. 1 is a block diagram of digital video signal receiver supportingfault tolerance through the provision of backup or alternatefunctionalities; and

FIG. 2 is a flow diagram illustrating operation of a fault detectioncircuit for the receiver of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of digital video signal receiver 10(commonly known in the art as a “set-top box”) supporting faulttolerance through the provision of backup or alternate functionalities.The receiver 10 includes an input 12 that, for example, comprises acoaxial connection 14 for a free air antenna or satellite dish orcombination thereof. The RF audio/video signal received throughconnection 14 is processed by a splitter 16 (for example, a four-waywideband splitter known in the art). The splitter 16 includes aplurality of outputs including two terrestrial signal outputs 18 and 20and two satellite signal outputs 22 and 24.

The first terrestrial signal output 18 is connected to a firstterrestrial front end receiver circuit 26. The second terrestrial signaloutput 20 is connected to a second terrestrial front end receivercircuit 28. The second terrestrial front end receiver circuit 28 maycomprise a backup or alternate circuit for the first terrestrial frontend receiver circuit 26. In other words, the first terrestrial front endreceiver circuit 26 is the primary front end circuit functionality andthe second terrestrial front end receiver circuit 28 is a secondary orredundant front end circuit functionality. The first and secondterrestrial front end receiver circuits 26 and 28 each include an enablecontrol input 30 fed by a terrestrial enable signal (Chip_Enable_T) 32.In the illustrated implementation, the first and second terrestrialfront end receiver circuits 26 and 28 are enabled in a mutuallyexclusive manner. The enabled one of the first and second terrestrialfront end receiver circuits 26 and 28 generates a received signalTS_Terr for further processing.

The first satellite signal output 22 is connected to a first satellitefront end receiver circuit 34. The second satellite signal output 24 isconnected to a second satellite front end receiver circuit 36. Thesecond satellite front end receiver circuit 36 may comprise a backup oralternate circuit for the first satellite front end receiver circuit 34.In other words, the first satellite front end receiver circuit 34 is theprimary front end circuit functionality and the second satellite frontend receiver circuit 36 is a secondary or redundant front end circuitfunctionality. The first and second satellite front end receivercircuits 34 and 36 each include an enable control input 38 fed by asatellite enable signal (Chip_Enable_S) 40. In the illustratedimplementation, the first and second satellite front end receivercircuits 34 and 36 are enabled in a mutually exclusive manner. Theenabled one of the first and second satellite front end receivercircuits 34 and 36 generates a received signal TS_Sat for furtherprocessing.

Antenna control, such as that known in the art as smart-antenna orsatellite multi-switch, is exemplified here with low-noise block (LNB)control. The digital video signal received through connection 14 isfurther received by a first LNB downconverter control circuit 42 and asecond LNB downconverter control circuit 44. The second LNBdownconverter control circuit 44 may comprise a backup or alternatecircuit for the first LNB downconverter control circuit 42. In otherwords, the first LNB downconverter control circuit 42 the primarydownconverter circuit and the second LNB downconverter control circuit44 is a secondary or redundant downconverter circuit functionality. Thefirst and second LNB downconverter control circuits 42 and 44 eachinclude an enable control input 46 fed by a downconverter enable signal(Chip_Enable_L) 48. In the illustrated implementation, the first andsecond LNB downconverter control circuits 42 and 44 are enabled in amutually exclusive manner with the SoC using an antenna bi-directionalcontrol protocol (e.g., DiSEqC 2.0) to identify the LNBs uniquely. Theenabled one of the first and second LNB downconverter control circuits42 and 44 generates a received signal LNB_Control for furtherprocessing.

The received TS_Terr signal, TS_Sat signal and LNB_Control signal arepassed to a System on Chip (SoC) 50 which functions to process thesignals and generate an audio/video output signal. The audio/videosignal processing performed by the System on Chip (SoC) 50 is well knownto those skilled in the art and will not be discussed in detail herein.Generally speaking, the System on Chip (SoC) 50 performs the standardsignal processing functions with respect to the received TS_Terr signaland TS_Sat signal to generate the output audio/video signal.

The System on Chip (SoC) 50 further comprises a fault detection circuit(Fault) 52 which determines whether there is a fault in, failure of, ormal-performance by a primary functionality of the system 10, and inresponse to such a determination activate the provided backup oralternate functionality. The fault detection circuit 52 operates toprocess sensed values for operational parameters of the receiver 10, andin particular sensed values concerning operation of the first and secondterrestrial front end receiver circuits 26 and 28, the first and secondsatellite front end receiver circuits 34 and 36 and the first and secondLNB downconverter control circuits 42 and 44. The processing performedby the fault detection circuit 52 makes a fault, failure ormal-performance determination based on the sensed values for operationalparameters and controls the generation of the terrestrial enable signal(Chip_Enable_T) 32, satellite enable signal (Chip_Enable_S) 40 anddownconverter enable signal (Chip_Enable_L) 48 so as to selectivelyenable one of the first and second terrestrial front end receivercircuits 26 and 28, one of the first and second satellite front endreceiver circuits 34 and 36 and one of the first and second LNBdownconverter control circuits 42 and 44. For example, in the event thefault detection circuit 52 detects a failure of the first terrestrialfront end receiver circuit 26 as indicated by processing of the sensedvalues for circuit 26 operational parameters, the logic state of theterrestrial enable signal (Chip_Enable_T) 32 is switched to enableoperation of the second terrestrial front end receiver circuit 28.

The fault detection circuit 52 may comprise a microprocessor ormicrocontroller circuit within the SoC 50 that is configured, forexample, through an appropriate programming, to process receivedoperational parameter data as discussed herein and make a faultdetection determination.

The System on Chip (SoC) 50 further includes measurement circuitry 54which is configured to measure operational parameters of the first andsecond terrestrial front end receiver circuits 26 and 28, the first andsecond satellite front end receiver circuits 34 and 36 and the first andsecond LNB downconverter control circuits 42 and 44. Examples ofoperational parameters measured by the measurement circuitry 54 includeCarrier to Noise ratio (C/N), Bit Error Rate (BER), Tuner frequencyoffset, Polarity Voltage level, DiSEqC delay, and the like. The measuredvalues of the operational parameters are reported to the fault detectioncircuit 52 which, as described generally above, processes the values,makes a fault, failure or mal-performance determination, and controlsgeneration of the enable signals to make a selection between primary andbackup or alternate functionalities supported by the system 10.

The measurement circuit 54 may comprise any circuit configured to senseoperation of the system 10 and its component parts and through suchsensing make a measurement concerning performance with respect todesired operational parameters. Examples of the circuitry and functionsof the measurement circuit 54 include Ts_Ter Error, Ts_Sat Error, VideoTreshold of Visibility (ToV) error, maximum or minimum Automatic GainControl (AGC), and the like.

Reference is now made to FIG. 2 which illustrates a flow diagram foroperation of the fault detection circuit 52. This flow may, for example,represent the programming of the fault detection circuit 52 whenimplemented in the form of a microprocessor or microcontroller circuitwithin the SoC 50.

In step 100, initialization is made with respect to verifying theoperation of primary functionality provided by the first LNBdownconverter control circuit 42. This initialization includes using themeasurement circuitry 54 to measure values for certain predefinedoperational parameters of the first LNB downconverter control circuit42. Examples of measureable operational parameters for a LNBdownconverter control circuit include DiSEqC delay, DiSEqC Transmissionerror, Polarity voltage level, and the like. A mean equivalence value(EqVal) is calculated from the measured operational parameter values ina weighted comparison with ideal or nominal or expected parameter valuesfor the LNB downconverter control circuit (i.e., a reference circuit).

The calculated mean equivalence value (LNB SME=EqVal) is then comparedin step 102 with a set mean equivalence (Reference SME) value for anidealized representation of the first LNB downconverter control circuit42. If the mean equivalence value exceeds the reference SME value, thefirst LNB downconverter control circuit 42 is considered to be operatingproperly and the fault detection circuit 52 moves to step 104 andenables the first LNB downconverter control circuit 42, for example, bysetting Chip_Enable_L to a first logic state.

If the mean equivalence value (LNB SME) does not exceed the referenceSME value, the fault detection circuit 52 moves to step 106 and aninitialization is made with respect to verifying the operation of thesecond LNB downconverter control circuit 44. This initializationincludes measuring values for certain predefined operational parametersof the second LNB downconverter control circuit 44. Examples ofmeasureable operational parameters for a LNB downconverter controlcircuit include DiSEqC delay, DiSEqC Transmission error, Polarityvoltage level, and the like. A mean equivalence value (EqVal) iscalculated from the measured operational parameter values in a weightedcomparison with ideal or nominal or expected parameter values for theLNB downconverter control circuit (i.e., a reference circuit).

The calculated mean equivalence value (LNB_ALT SME=EqVal) is thencompared in step 108 with a set mean equivalence (Reference SME) valuefor an idealized representation of the second LNB downconverter controlcircuit 44 (which may, for example, be identical to the idealizedrepresentation of the first LNB downconverter control circuit 42). Ifthe calculated mean equivalence value exceeds the reference SME value,the second LNB downconverter control circuit 44 is considered to beoperating properly and the fault detection circuit 52 moves to step 110and enables the second LNB downconverter control circuit 44 (as a backupor alternate functionality to the first LNB downconverter controlcircuit 42), for example, by setting Chip_Enable_L to a second logicstate. If the calculated mean equivalence value does not exceed thereference SME value, the fault detection circuit 52 moves to step 112 toissue a system fault notice.

From step 110 (or alternatively from step 112), the fault detectioncircuit 52 moves to step 114 where initialization is made with respectto verifying the operation of primary functionality provided by thefirst satellite front end receiver circuit 34. This initializationincludes measuring values for certain predefined operational parametersof the first satellite front end receiver circuit 34. Examples ofmeasureable operational parameters for a satellite front end receivercircuit include Insertion Loss (IL), Return Loss (RL), Adjacent ChannelInterferance (ACI), Low RF Bit Error Rate (BER), High RF BER, and thelike. A mean equivalence value (EqVal) is calculated from the measuredoperational parameter values in a weighted comparison with ideal ornominal or expected parameter values for the satellite front endreceiver circuit (i.e., a reference circuit).

The calculated mean equivalence value (Sat FE SME=EqVal) is thencompared in step 116 with a set mean equivalence (Reference SME) valuefor an idealized representation of the first satellite front endreceiver circuit 34. If the calculated mean equivalence value exceedsthe reference SME value, the first satellite front end receiver circuit34 is considered to be operating properly and the fault detectioncircuit 52 moves to step 118 and enables the first satellite front endreceiver circuit 34, for example, by setting Chip_Enable_S to a firstlogic state.

If the calculated mean equivalence value does not exceed the referenceSME value, the fault detection circuit 52 moves to step 120 and aninitialization is made with respect to verifying the operation of thesecond satellite front end receiver circuit 36. This initializationincludes measuring values for certain predefined operational parametersof the second satellite front end receiver circuit 36. Examples ofmeasureable operational parameters for a satellite front end receivercircuit include Insertion Loss (IL), Return Loss (RL), Adjacent ChannelInterferance (ACI), Low RF Bit Error Rate (BER), High RF BER, and thelike. A mean equivalence value (EqVal) is calculated from the measuredoperational parameter values in a weighted comparison with ideal ornominal or expected parameter values for the satellite front endreceiver circuit (i.e., a reference circuit).

The calculated mean equivalence value (Sat FE_ALT SME=EqVal) is thencompared in step 122 with a set mean equivalence (Reference SME) valuefor an idealized representation of the second satellite front endreceiver circuit 36 (which may, for example, be identical to theidealized representation of the first satellite front end receivercircuit 34). If the calculated mean equivalence value exceeds thereference SME value, the second satellite front end receiver circuit 36is considered to be operating properly and the fault detection circuit52 moves to step 124 and enables the second satellite front end receivercircuit 36 (as a backup or alternate functionality to the firstsatellite front end receiver circuit 34), for example, by settingChip_Enable_S to a second logic state. If the calculated meanequivalence value does not exceed the reference SME value, the faultdetection circuit 52 moves to step 112 to issue a system fault notice.

From step 122 (or alternatively from step 112), the fault detectioncircuit 52 moves to step 126 where initialization is made with respectto verifying the operation of the first terrestrial front end receivercircuit 26. This initialization includes measuring values for certainpredefined operational parameters of the first terrestrial front endreceiver circuit 26. Examples of measureable operational parameters fora terrestrial front end receiver circuit include Insertion Loss (IL),Return Loss (RL), Adjacent Channel Interferance (ACI), Low RF Bit ErrorRate (BER), High RF BER, and the like. A mean equivalence value (EqVal)is calculated from the measured operational parameter values in aweighted comparison with ideal or nominal or expected parameter valuesfor the terrestrial front end receiver circuit (i.e., a referencecircuit).

The calculated mean equivalence value (Terr FE SME=EqVal) is thencompared in step 128 with a set mean equivalence (Reference SME) valuefor an idealized representation of the first terrestrial front endreceiver circuit 26. If the calculated mean equivalence value exceedsthe reference SME value, the first terrestrial front end receivercircuit 26 is considered to be operating properly and the faultdetection circuit 52 moves to step 130 and enables the first terrestrialfront end receiver circuit 26, for example, by setting Chip_Enable_T toa first logic state.

If the calculated mean equivalence value does not exceed the referenceSME value, the fault detection circuit 52 moves to step 132 and aninitialization is made with respect to verifying the operation of thesecond terrestrial front end receiver circuit 28. This initializationincludes measuring values for certain predefined operational parametersof the second terrestrial front end receiver circuit 28. Examples ofmeasureable operational parameters for a terrestrial front end receivercircuit include Insertion Loss (IL), Return Loss (RL), Adjacent ChannelInterferance (ACI), Low RF Bit Error Rate (BER), High RF BER. A meanequivalence value (EqVal) is calculated from the measured operationalparameter values in a weighted comparison with ideal or nominal orexpected parameter values for the terrestrial front end receiver circuit(i.e., a reference circuit).

The calculated mean equivalence value (Terr FE_ALT SME=EqVal) is thencompared in step 134 with a set mean equivalence (Reference SME) valuefor an idealized representation of the second terrestrial front endreceiver circuit 28 (which may, for example, be identical to theidealized representation of the first terrestrial front end receivercircuit 26). If the calculated mean equivalence value exceeds thereference SME value, the second terrestrial front end receiver circuit28 is considered to be operating properly and the fault detectioncircuit 52 moves to step 136 and enables the second terrestrial frontend receiver circuit 28 (as a backup or alternate functionality to thefirst terrestrial front end receiver circuit 26), for example, bysetting Chip_Enable_T to a second logic state. If the calculated meanequivalence value does not exceed the reference SME value, the faultdetection circuit 52 moves to step 112 to issue a system fault notice.

After testing each of the functionalities as described above, the faultdetection circuit 52 ends at step 138 with a completed verification andselective enabling of the primary and backup or alternatefunctionalities supported by the system 10.

The process of FIG. 2 may be performed at system configuration orinitialization, such as at start-up. Alternatively, the process of FIG.2 may be performed during system operation. The process of FIG. 2 may beperformed one time for each system activation, or alternativelyperformed multiple times, including being performed periodically, ifdesired. The order of testing the various functionalities of the system10 is exemplary only.

The operations performed in steps 100, 102, 16, 108, 114, 116, 120, 122,126, 128, 132 and 134 comprise processes for identifying equivalencebetween systems. In particular, the processes determine equivalencebetween the system functionality and an idealized (or nominal)functionality based on a predetermined set of parameters, measured andexpected values for those parameters, and a relative weighting of thoseparameters. The system functionality may then be identified as beingnegligibly dissimilar from the idealized (or nominal) functionality (andthus enabled for operation) or reasonably unlike the idealized (ornominal) functionality (and thus indicating the presence of a fault). Inresponse to fault detection, the system functionality may be disabledfrom operation and, if supported by the system, replaced by a backup oralternate functionality.

The system 10 accordingly may perform, as a consistency/verificationcheck using its driver software or embedded firmware in the form of thefault detection circuit 52, for example as part of aninitialization/configuration process for the SoC 50, an equivalence testto verify that functionalities, devices and blocks within the system 10are working as expected. The fault detection circuit 52 can also usethis equivalence testing to enable fault tolerance on key systemfunctionalities, devices and blocks; that is, if a functionality, deviceor block of the system seems to have failed in view of the equivalencetesting, an available alternate functionality, device or block may beactivated in its place. The program flow for such a system may bedescribed in accordance with the following pseudo code (see, also FIG.2):

0) SoC system has N systems (System); each with 0 or more alternates(AltSystem) 1) Initialize system matrix (array of parameter set valuesand weights as well as the respective reference value sets); identifythe Set Mean Equivalence (SME) value, 2) For i=1;N;i++ if !(EqVal ofSystem(i) ≧ Mean Set Equivalence) { Set System(i) inactive) if AltSystem(i) if !(EqVal of AltSystem(i) ≧ Mean Set Equivalence) return SoCfailure else set AltSystem(i) active } else set System(i) active

A description will now be provided as to the details of making theequivalence test.

A reference system functionality is identified by a basis set ofparameters. The ideal (or nominal) representation of that referencesystem functionality has an expected value associated for each of theseparameters. The expected value of any parameter is derived from theapplicable distribution of possible values associated with correct (orpermissible) operation of the reference functionality. Those skilled inthe art will recognize that typical distributions used in this contextinclude: a NORMAL distribution which is defined by Mean, StandardDeviation parameter values, a POISSON distribution which is defined byMean parameter values, a TRIANGULAR distribution which is defined byMinimum, Mode, and Maximum parameter values, and a UNIFORM distributionwhich is defined by Minimum and Maximum parameter values. Otherdistributions known in the art could also be used with respect to agiven parameter value.

Three sets are used for defining the reference system functionality andcalculating equivalence.

A first set is referred to as the Parameter Set and is designated asfollows:

Parameter Set: {Param1, Param2, . . . , ParamN}

The membership of the Parameter Set includes desired reference systemfunctionality parameters (such as, for example, operational parameters).

A second set is referred to as the Normative Value Set and is designatedas follows:

Normative Value Set: {ExpectedVal1, ExpectedVal2, . . . , ExpectedValN}

The membership of the Normative Value Set includes the expected value ofthe parameter identified in the Parameter Set. The expected value is asingle value for the identified parameter. Preferably, the expectedvalue is expressed by a distribution. As mentioned above, examples ofdistributions for use in the Normative Value Set include: a NORMALdistribution, a POISSON distribution, a TRIANGULAR distribution, and aUNIFORM distribution.

A third set is referred to as the Weighting Set and is designated asfollows:

Weighting Set: {W1, W2, . . . , WN}

The membership of the Weighting Set includes a weight value assigned toeach parameter identified in the Parameter Set. The weight valuereflects the fraction that functionality parameter and its valuecontributes to the equivalence determination. Thus, a weight value of 4,for example, for Param1 in a Weighting Set: {4,1,1,4} indicates that theanalysis of ExpectedVal1 contributes 40% (4/{4+1+1+4}) to theequivalence determination.

The last factor considered in making the equivalence determination isthe Set Mean Equivalence value which is designated as follows:

Set Mean Equivalence >=P %

The value of P represents a percentage value which must be equaled orexceeded in order for equivalence between the system functionality undertest and the reference system functionality to be found.

In accordance with the operations performed in steps 100, 102, 16, 108,114, 116, 120, 122, 126, 128, 132 and 134 of FIG. 2, certain operationalparameters for the functionalities of the system 10 are identified todefine, for each such functionality, a Parameter Set: {Param1, Param2, .. . , ParamN}. Furthermore, with respect to an ideal or nominaloperation of that system functionality (i.e., the referencefunctionality), an expected value is provided for each parameter todefine the Normative Value Set: {ExpectedVal1, ExpectedVal2, . . . ,ExpectedValN}. Also, a weight value is assigned to each parameteridentified in the Parameter Set to define the Weighting Set: {W1, W2, .. . , WN}. Lastly, a Set Mean Equivalence percentage P value isassigned.

To make the equivalence determination between an actual functionality ofthe system 10 that is under test and the reference functionality, theparameters are measured by the measurement circuitry 54 of the SoC 50and a measured parameter set, referred to as the A Set, for thefunctionality under test is designated as follows:

A Set: {A1, A2, . . . , AN}

wherein the membership of the A Set is the measurement circuitry 54measured value of the parameter identified in the Parameter Set. It willbe understood that the measured value could comprise a single measuredvalue, or a calculated distribution (for example, an average) withrespect to a plurality of measured values over a give time period.

To determine the equivalence level between the actual functionality insystem 10 defined by {A1, A2, . . . , AN} under test and the referencefunctionality defined by {ExpectedVal1, ExpectedVal2, . . . ,ExpectedValN}, an equivalence metric in the form of an equivalent value(EqVal) is calculated as a sum of the relative percentages of theexpected values divided by the number of values as follows:

$\begin{matrix}{\mspace{79mu} {{{EqVal} = {\frac{\sum\limits_{i = 1}^{N}\lbrack {{R( {{{Expected}{Val}}_{i},A_{i}} )} \cdot W_{i}} \rbrack}{\sum\limits_{i = 1}^{N}W_{i}} \cdot 100}}\mspace{79mu} {{wherein}\text{:}}{{R( {{ExpectedVali},{Ai}} )} = {\min \{ {{{ExpectedVal}_{i}/A_{i}},{A_{i}/{ExpectedVal}_{i}}} \}}}}} & {{Eq}.\mspace{14mu} (1)}\end{matrix}$

If the calculated EqVal meets or exceeds the Set Mean Equivalencepercentage P value, then the actual functionality in system 10 isconsidered to have equivalence with the ideal or nominal operation ofthat system (reference) functionality. In other words, there is noinstance of a fault, failure or mal-performance. In the context of theFIG. 2 implementation, the tests in steps 102, 108, 116, 122, 128 or 134would be satisfied and the given functionality would be enabled foroperation. Conversely, if the calculated EqVal does not meet or exceedthe Set Mean Equivalence percentage P value, then the actualfunctionality in system 10 is considered to not have equivalence withthe ideal or nominal operation of that system (reference) functionality.In other words, there is an instance of a fault, failure ormal-performance. In the context of the FIG. 2 implementation, the testsin steps 102, 108, 116, 122, 128 or 134 would be failed and the givenfunctionality would be not be enabled for operation.

The foregoing may be better understood by reference to a specificexample. Consider a system, like that of system 10 in FIG. 1, comprisinga satellite receiver device. That device has been produced and passescertain measurable performance specifications for key functionalities.Those measurable performance specifications comprise Insertion Loss(IL), Return Loss (RL), ACI Performance (ACI), Low RF performance (LRF),and High RF performance (HRF). The Parameter Set is accordingly definedas:

Parameter Set: {IL, RL, ACI, LRF, HRF}

Measured historical data of the qualified (correctly operating) systemin production indicates expected values (ExpectedVal) for theperformance parameters as follows: Insertion Loss (IL)=0.25 dB; ReturnLoss (RL)=−13 dB, ACI Performance (ACI)=BER of 2.2e-9, Low RFperformance (LRF)=BER of 2.1e-9, and High RF performance (HRF)=BER of2.9e-9. Thus, the Normative Value Set for the qualified system as areference functionality would be defined as:

Normative Value Set: {0.25 dB, −13 dB, BER of 2.2e-9, BER of 2.1e-9, BERof 2.9e-9}.

Weight values are assigned to each parameter identified in the ParameterSet to produce a Weighting Set defined as:

Weighting Set: {1, 4, 5, 10, 10}.

This particular weighting set indicates that a greater weight forcorrespondence between the measured values of the system under test tothe expected values is being given to the Low RF performance (LRF) andHigh RF performance (HRF) than the other parameters.

In order for the actual functionality of a system 10 to have equivalencewith the ideal or nominal operation of that system functionality a SetMean Equivalence of greater than 90% is required. Thus, P>90%.

The measurement circuitry 54 of the SoC 50 is configured to makemeasurements on the Insertion Loss (IL), Return Loss (RL), ACIPerformance (ACI), Low RF performance (LRF), and High RF performance(HRF) on the primary functionality of the system 10 (the functionalityunder test). A measured parameter set, referred to as the A Set, is thusobtained from measurement circuitry 54 parameter measurements asfollows:

A Set: {0.23, −12.0, 2.9e-9, 2.3e-9, 3.1e-9}

The calculated equivalence metric EqVal (from Eq. 1) for the primaryfunctionality would thus be:

EqVal=SUM{0.92*1/30, 0.92*4/30, 0.75*5/30, 0.91*10/30, 0.93*10/30}*100

EqVal={0.031+0.123+0.125+0.303+0.310}*100=0.892*100

EqVal=89.2%

Because the EqVal of 89.2% is less than the Set Mean Equivalence valueof 90%, this would be indicative of detection of a fault in, failure of,or mal-performance by a tested functionality of the system 10. Inresponse thereto, the fault detection circuit 52 would instead activatethe backup or alternate functionality if available. If no backup oralternate functionality is available, then a system fault may beindicated.

In connection with activating the backup or alternate functionality, themeasurement circuitry 54 of the SoC 50 would further be configured tomake measurements on the Insertion Loss (IL), Return Loss (RL), ACIPerformance (ACI), Low RF performance (LRF), and High RF performance(HRF) on the backup or alternate functionality of the system 10. Ameasured parameter set, referred to as the A Set, is thus obtained frommeasurement circuitry 54 parameter measurements as follows:

A Set: {0.24, −12.5, 2.9e-9, 2.2e-9, 3.0e-9}

The calculated equivalence metric EqVal (from Eq. 1) for the backup oralternate functionality would thus be:

EqVal=SUM{0.96*1/30, 0.96*4/30, 0.76*5/30, 0.95*10/30, 0.97*10/30}*100

EqVal={0.032+0.128+0.126+0.317+0.323}*100=0.926*100

EqVal=92.6%

Because the EqVal of 92.6% meets or exceeds the Set Mean Equivalencevalue of 90%, this would be indicative that the backup or alternatefunctionality of the system 10 is operating properly. This backup oralternate functionality may thus be enabled to replace the faulty testedfunctionality of the system 10.

The foregoing description has provided by way of exemplary andnon-limiting examples a full and informative description of theexemplary embodiment of this invention. However, various modificationsand adaptations may become apparent to those skilled in the relevantarts in view of the foregoing description, when read in conjunction withthe accompanying drawings and the appended claims. However, all such andsimilar modifications of the teachings of this invention will still fallwithin the scope of this invention as defined in the appended claims.

What is claimed is:
 1. A system, comprising: a primary functionality; abackup functionality for said primary functionality; a measurementcircuit configured to measure a plurality of operational parametervalues of the primary functionality; and a fault detection circuitconfigured to determine a level of equivalence between the operation ofthe primary functionality and a reference functionality based on aweighted comparison of said measured plurality of operational parametervalues of the primary functionality to a corresponding plurality ofreference operational parameter values for the reference functionality,said fault detection circuit further configured to identify a fault insaid primary functionality based on the equivalence determination andactivate the backup functionality in response thereto.
 2. The system ofclaim 1, wherein the determined level of equivalence is calculated basedon the following formula:$\frac{\sum\limits_{i = 1}^{N}\lbrack {{R( {{ExpectedVal}_{i},A_{i}} )} \cdot W_{i}} \rbrack}{\sum\limits_{i = 1}^{N}W_{i}}$wherein ExpectedVal is the reference operational parameter value; A isthe measured operational parameter value; W is the weight; andR(x,y)=min {x/y, y/x}.
 3. The system of claim 2, wherein no fault isidentified if EqVal meets or exceeds a threshold.
 4. The system of claim2, wherein a fault is identified if EqVal is less than a threshold. 5.The system of claim 1, wherein no fault is identified if operation ofthe primary functionality and the reference functionality are determinedto be equivalent.
 6. The system of claim 1, wherein a fault isidentified if operation of the primary functionality and the referencefunctionality are determined not to be equivalent.
 7. The system ofclaim 1, wherein said measurement circuit is further configured tomeasure the plurality of operational parameter values of the backupfunctionality; and wherein the fault detection circuit is furtherconfigured to determine a level of equivalence between the operation ofthe backup functionality and the reference functionality based on aweighted comparison of said measured plurality of operational parametervalues of the backup functionality to the corresponding plurality ofreference operational parameter values for the reference functionality,and wherein said fault detection circuit is further configured toidentify a fault in said backup functionality based on the equivalencedetermination.
 8. The system of claim 1, wherein the primaryfunctionality is a front end circuit, and wherein the backupfunctionality is a backup front end circuit, said front end circuithaving operational parameters selected from the group consisting ofInsertion Loss, Return Loss, ACI Performance, Low RF performance, andHigh RF performance.
 9. A method, comprising: measuring a plurality ofoperational parameter values of a primary functionality; determining alevel of equivalence between the operation of the primary functionalityand a reference functionality based on a weighted comparison of saidmeasured plurality of operational parameter values of the primaryfunctionality to a corresponding plurality of reference operationalparameter values for the reference functionality; detecting a fault insaid primary functionality based on the equivalence determination; andactivating a backup functionality in response to the detected fault. 10.The method of claim 1, wherein determining the level of equivalencecomprises calculating an equivalence value based on the followingformula:$\frac{\sum\limits_{i = 1}^{N}\lbrack {{R( {{ExpectedVal}_{i},A_{i}} )} \cdot W_{i}} \rbrack}{\sum\limits_{i = 1}^{N}W_{i}}$wherein ExpectedVal is the reference operational parameter value; A isthe measured operational parameter value; W is the weight; andR(x,y)=min {x/y, y/x}.
 11. The method of claim 10, wherein detecting thefault comprises identifying no fault if EqVal meets or exceeds athreshold.
 12. The method of claim 10, wherein detecting the faultcomprises identifying a fault if EqVal is less than a threshold.
 13. Themethod of claim 9, wherein detecting the fault comprises determiningwhether the operation of the primary functionality is equivalent tooperation of the reference functionality.
 14. The method of claim 9,further comprising: measuring a plurality of operational parametervalues of the backup functionality; determining a level of equivalencebetween the operation of the backup functionality and the referencefunctionality based on a weighted comparison of said measured pluralityof operational parameter values of the backup functionality to acorresponding plurality of reference operational parameter values forthe reference functionality; detecting a fault in said backupfunctionality based on the equivalence determination.
 15. The method ofclaim 9, wherein the primary functionality is a front end circuit, andwherein the backup functionality is a backup front end circuit, saidfront end circuit having operational parameters selected from the groupconsisting of Insertion Loss, Return Loss, ACI Performance, Low RFperformance, and High RF performance.
 16. A method for determining anequivalence level to a reference system defined by a plurality of valuesfor operational parameters, comprising: measuring a plurality of valuesfor corresponding operational parameters of a system under test;calculating an equivalence metric as a sum of relative percentages ofthe operational parameter values for the system under test versus theoperational parameter values for the reference system; and controllingoperation of the system under test in response to the calculatedequivalence metric.
 17. The method of claim 16, wherein controllingcomprises switching to a backup system if the calculated equivalencemetric indicates a failure of the system under test.
 18. The method ofclaim 16, wherein the equivalence metric is calculated in accordancewith the following formula:$\frac{\sum\limits_{i = 1}^{N}\lbrack {{R( {{ExpectedVal}_{i},A_{i}} )} \cdot W_{i}} \rbrack}{\sum\limits_{i = 1}^{N}W_{i}}$wherein ExpectedVal is the operational parameter value for the referencesystem; A is the measured operational parameter value for the systemunder test; W is a weight; and R(x,y)=min {x/y, y/x}.
 19. The method ofclaim 16, wherein the sum of relative percentages is a weighted sum ofrelative percentages.
 20. The method of claim 16, further comprisingcomparing the calculated equivalence metric against a threshold, andwherein controlling comprises enabling operation of the system undertest if the calculated equivalence metric meets or exceeds thethreshold.
 21. The method of claim 20, wherein controlling comprisesdisabling operation of the system under test and enabling a backupsystem if the calculated equivalence metric is less than the threshold.22. Apparatus, comprising: a system under test; a measurement circuitconfigured to measure a plurality of values for operational parametersof a system under test, said operational parameters corresponding to aplurality of values for operational parameters of a reference system;and a control circuit configured to calculate an equivalence metric as asum of relative percentages of the operational parameter values for thesystem under test versus the operational parameter values for thereference system and further control operation of the system under testin response to the calculated equivalence metric.
 23. The apparatus ofclaim 22, further comprising a backup system selectable to replace thesystem under test, said control circuit configured to switch to thebackup system if the calculated equivalence metric indicates a failureof the system under test.
 24. The apparatus of claim 22, wherein theequivalence metric is calculated in accordance with the followingformula:$\frac{\sum\limits_{i = 1}^{N}\lbrack {{R( {{ExpectedVal}_{i},A_{i}} )} \cdot W_{i}} \rbrack}{\sum\limits_{i = 1}^{N}W_{i}}$wherein ExpectedVal is the operational parameter value for the referencesystem; A is the measured operational parameter value for the systemunder test; W is a weight; and R(x,y)=min {x/y, y/x}.
 25. The apparatusof claim 22, wherein the sum of relative percentages is a weighted sumof relative percentages.
 26. The apparatus of claim 22, wherein thecontrol circuit is further configured to compare the calculatedequivalence metric against a threshold, and wherein controllingoperation comprises enabling operation of the system under test if thecalculated equivalence metric meets or exceeds the threshold.
 27. Theapparatus of claim 26, wherein controlling comprises disabling operationof the system under test and enabling a backup system if the calculatedequivalence metric is less than the threshold.